title: Effect of salivary phosphate-binding chewing gum on serum phosphate in chronic kidney disease.
abstract: OBJECTIVE
  Serum phosphate (P) has been linked to adverse events in patients with chronic kidney disease. Salivary phosphate (Psal) has been proposed as a potential target of therapy with a chitosan-containing chewing gum.
  
  
  METHODS
  We conducted several pilot studies to characterize Psal and its relationship with kidney function and subsequently conducted two clinical efficacy studies: a double-blind placebo-controlled trial in patients with end-stage renal disease (ESRD) and an open-label trial in those with stage 3-4 CKD.
  
  
  RESULTS
  Pilot studies demonstrated no relationship between the level of kidney function and Psal. Mean Psal was approximately 6.46 mmol/l across the entire spectrum of kidney function. Passive saliva collection demonstrated higher Psal concentration as compared to active collection. There was no evidence of diurnal variation in Psal. Twice daily 20 mg chitosan gum over 4 weeks reduced serum P by 0.065 mmol/l in the double-blind, placebo-controlled trial in ESRD (p = NS vs. placebo). In an open-label extension in these subjects, 40 mg chitosan gum three times daily reduced serum P by 0.065 mmol/l (p = 0.03 vs. end of washout). In a 2-week open-label trial in patients with CKD not on dialysis, 20 mg chitosan gum given three times daily reduced serum P by 0.05 mmol/l (p = 0.003 vs. day 1). Neither trial demonstrated any significant change in Psal with chitosan gum.
  
  
  CONCLUSIONS
  Psal concentration is approximately 4-5 times that of serum P and is not related to glomerular filtration rate. Chitosan chewing gum resulted in a reduction of serum P by approximately 0.05-0.065 mmol/l but had no effect on Psal concentration.
authors.affiliation: Denver Nephrologists, PC Denver, Colo., USA. gablock@denverneph.net
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Block
authors.forename: Martha S
authors.initials: MS
authors.lastname: Persky
authors.forename: Beth M
authors.initials: BM
authors.lastname: Shamblin
authors.forename: Marissa F
authors.initials: MF
authors.lastname: Baltazar
authors.forename: Bhupinder
authors.initials: B
authors.lastname: Singh
authors.forename: Amit
authors.initials: A
authors.lastname: Sharma
authors.forename: Pablo
authors.initials: P
authors.lastname: Pergola
authors.forename: Gerard
authors.initials: G
authors.lastname: Smits
authors.forename: Maria C
authors.initials: MC
authors.lastname: Comelli
mesh_terms: D000284:Administration, Oral; D000368:Aged; D002638:Chewing Gum; D048271:Chitosan / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D054559:Hyperphosphatemia / Q000175:diagnosis* / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000032:analysis* / Q000097:blood; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy*; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D002638:Chewing Gum; D010710:Phosphates; D048271:Chitosan